Traditional image or photo capturing techniques may allow only one focus per image, thus objects not in the same focus in an image may come out as blurry or unclear. Since multiple images of the same scene captured with distinct focus positions may carry details for each object, focus stacking (FS) may be used to combine details in a plurality of images into one image and make all objects in the scene perceived in details or a non-blurry fashion. The idea of this digital image technique is to obtain images closer to human visual perception. In effect, FS may increase the depth of field in an image with post-capture processing. Applications of FS may include macro photography and optical microscopy. Some traditional FS processes may use a high-end camera on a fixed position to take pictures, followed by a comprehensive off-site computing process. In another approach, a light-field camera, which may sometimes be called a plenoptic camera, has been used in recent years to realize FS, although this approach may require advanced micro-sensor technologies and comprehensive post-capture computations.
With the advancement of technologies, the resolution, linearity, and clearness of cameras in mobile devices have improved today. The advancement has also lead to increased aperture sizes, higher number of sensors, more choices of focus modes and points with a limited depth of field each, etc. For photography applications on mobile platforms or in mobile devices (e.g., cell phone, smartphone, tablet, hand-held camera, laptop), one touch of a screen may indicate a region of interest in the scene with a certain focus position. One image may be captured in one shot with a single focus position. There has yet to be on-site FS features on mobile devices readily available in the market. Thus, it may be desirable to integrate on-site FS capabilities into mobile devices to enhance user experience.